Considering that the kinetics of GDNF expression differed from that of luciferase in both our study and that investigating CK30 NPs as a delivery vehicle for GDNF rescue of dopaminergic neurons in a model of Parkinson’s disease [37,38], it is reasonable to speculate that in general the duration of transgene expression would depend on the protein expressed and its effect at higher doses on the expressing cells. This evidence concerns the gene GDNF and Parkinson disease.